BE674810A - - Google Patents

Description

       

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    "Refraotaire with binder oarbonétt
The present invention relates to a binder refractory and more particularly to a carbonaceous binder death-calcined refractory having improved physical properties and intended for use at high temperatures :.



   The change in the steelmaking industry from the hearth furnace steelmaking process to the relatively new basic process of oxygen steelmaking has posed significant challenges. new demands on the refurbishing industry in the desire to have high quality coating materials

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 new and improved ovens.

   New basic oxygen converters and other steelmaking furnaces have been used as refractories for new basic oxygen converters and for other steelmaking furnaces, preformed brick or bloos and adobe refractories. composed of dead-charred granular materials, such as dead-charred dolomite, dead-charred magnesia, or mixtures thereof, bound with a carbonaceous binder obtained from coal tar pitch. Nevertheless the ever increasing demands of producers. steel which require an increased useful life of these refraotaires materials having pitch as a binder require a continual improvement of the said refraotaires.



   The use of coal tar pitch as a carbonaceous binder capable of undergoing pyrolytic decomposition to form a carbonaceous binder for various products resistant to these high temperatures has long been known and practiced in certain fields of manufacture and is widely used.

   frequently in the production of specialized refractory materials. In accordance with the present invention, substantial improvements in furnace life can be achieved in such basic and granular refractories using pitch as a binder, such as dead charred dolomite or high charred magnesia. death by incorporating relatively small amounts of carbon black into the composition of the basic refraotaire. -
Consequently, the present invention proposes to provide:

   - an improved method of forming a. refraotary binder, as well as the refraotary produced by said

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 process ; - An improved process for producing a raw, uncooked basic refractory using pitch as a binder, which can be stored at will, and subsequently pyrolytically fired to decompose the pitch and form a carbonaceous binder refractory;

   - An improved basic refraotaire using as a binder coal tar pitch and composed for example of dolomite burnt to death, magnesia burnt to death, or a mixture of these bodies, and which can be used called rammed earth; - an improved foot like the one just described, which can be molded or pressed into various desired shapes for use as a brick or block in a basic oxygen converter or other steel production furnaces ,
Other objects and advantages of the invention will emerge from the following description,
In order to achieve the aforementioned goals and others,

   the invention comprises the characteristics described and set forth in the following text, which describes the invention in detail, without the illustrative description being able to be considered as limiting the invention to the various ways or means set out in which the invention can be put implemented.



   To practice the invention, the refractory particles are mixed with a carbonaceous material capable of pyrolytically decomposing to form a carbonaceous binder, and also with a relatively small amount of carbon, for example carbon black. We can use the

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 mixture in this form, for example as adobe. However, the mixture is usually shaped, for example by pressure, to give it a desired shape, for example a brick or block shape. For repairing or lining a furnace wall or hearth, a rammed earth or shaped article in the "raw" state can be employed either immediately or after storage and storage for a period of time.

   By subsequently bringing the furnace to an operating temperature, the carbonaceous material included in the mixture or in the brick decomposes pyrolitically or "ookéfio" to form a carbonaceous binder inside the rammed earth or the brick installed in the brick. oven. If desired, and especially in these bricks, the coking can be carried out, separately, before placing in the furnace.



   It has been recognized, both in the raw state and in the cooked or coked state, that the presence of carbon black improves the physical properties of rammed earth or mixtures, especially with regard to oxidation. crush resistance (binder strength) and density. It is not clear how the pulverized carbon material added to improve the binder repellent works.



  Apparently, the introduction of carbon into the composition of the granular refractor increases the binding properties of the pitch binder and as a result enhances the breakdown of the carbonaceous binder formed by the pyrolytic storm of the pitch.



   The refractory particles employed in accordance with the present invention are preferably death-calcined refractories, that is to say refractories which have been

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 calcined to a dense agglomerated state. Basic refractories such as dead-burned dolomite, dead-burned magnesia or mixtures of these bodies are preferably used.



   As indicated, the carbonaceous material employed is one which leaves a carbon residue when subjected to pyrolytic decomposition or cracking. This can occur at temperatures varying from about 370 to 1010 0. Within this temperature range, the cracking of the carbonaceous material forms a carbon film around and between the particles of the refractory. granular that binds particles to each other.

   The formation of the carbon film typically takes place inwardly from an exposed surface of the refractory, for example under the action of heat from a steelmaking reaction in a basic oxygen converter or in a basic oxygen oven, the progress towards the interior depending on the exposure conditions. The evaluation of any refraotaire using pitch as a binder is therefore carried out on samples which have been heated in such a way as to subject the pitch binder to decomposition or pyrolytic coking and using resistance as a comparison criterion. - resistance to crushing by compression of the refractories obtained.



   It is preferable that the carbonaceous materials employed are pitches and especially those derived from coal tar. Such coal tar pitch, for example, has softening points of from about 40 ° C to about 100 ° C., as measured by the ASTM method.

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 of test D-36-26. In some cases, coal tar itself has been used as a binder for these refractories, although coal tar pitch is usually preferred since it is essentially free of the low boiling constituents which are commonly used. usually found in coal tar. Some of the bituminous asphalts can be employed provided they have the property of pyrolytically decomposing to give an appreciable carbon residue.

   Many asphalts do not have this property, but distill entirely by heating and cannot be used for this reason.



  Accordingly, coal tar pitches are more generally employed as a binder in this type of refractory brick, since such pitches are less expensive and possess the desirable characteristic of cracking a higher proportion of carbon.



   All of the various kinds of oaruone blacks which are known in the art can be employed. In order to practice the present invention, it is also possible to employ other pulverulent carbons with an unobstructed crystalline structure. For example, coal and coke or powdered, finely divided graphite can be used, but these varieties of carbons are not as effective as carbon blacks. Carbon blacks which may be cited as an example include lamp blacks, flue blacks, furnace combustion blacks. gas or mineral oil, thermal blacks, acetylene blacks and the like. Some of these blacks are also referred to as impact blacks.

   In addition, these blacks can be used individually or in combination.

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 for addition to a granular basic refractory composition to improve the crush strength of the coked product, as well as density and other desirable properties a.



   The designations of the different types of carbon blacks mentioned in the previous paragraph are all designations known in the art. Descriptions of carbon blacks can be found, for example, in "Encyclopedia of Chemioal Technology", by Kirk and Othmer, The Interscience Enoyolopedia, Ino. New York, 1949, volume 3, pages 34 to 60. A further description of the different varieties and origins of carbon blacks is found in United States Patent No. 2,527,595 of October 31, 1950 in the name of Swallen and at ves.



   Carbon blacks include a group of non-crystalline carbon types, very finely divided, and composed of particle sizes smaller than the grinding dimensions. These blacks are also referred to as colloidal carbons because of their small particle size and their behavior in aqueous and organic liquid media. There are, however, certain carbon blacks which are within the scope of the present invention and which their particle sizes may cause to fall outside of what is generally considered to be the upper limit of colloidal sizes.



  Carbon blacks include products resulting from various industrial processes in which the hydrocarbons are subjected to partial combustion and non-oxidative heat treatment. Several types are produced which differ from each other in particle size,

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 The various types can be clearly differentiated in other points of view than particle size, for example some blacks are composed of very dense and well-defined particles, while others are more composed of flocculent particles agglomerated in masses. porous.



   The carbon blacks which have been found to be the most valuable for the practice of the invention possess the properties included in the following ranges:
 EMI8.1
 
<tb>
<tb> Diameter "of <SEP> particle <SEP> mean <SEP> 20 <SEP> to <SEP> 500 <SEP> millimicrons
<tb> Specific <SEP> area <SEP> 5 <SEP> "<SEP> 375 <SEP> m2 / gram
<tb> Content <SEP> in <SEP> volatile <SEP> materials <SEP> less <SEP> of <SEP> 14 <SEP>% <SEP> in <SEP> weight
<tb> Carbon <SEP> fixed <SEP> 85 <SEP> to <SEP> 99.5 <SEP>% <SEP> in <SEP> weight
<tb>
 
The following Table A indicates specific varieties of carbon blacks which have been employed.
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    BOARD
 EMI9.1
 
<tb> Carbon <SEP> <SEP> type <SEP> Specific <SEP> surface <SEP> Diameter '<SEP> the <SEP> particle <SEP> Oil absorption <SEP> <SEP> Content <SEP> in <SEP> my- <SEP> carbon <SEP> p @ <SEP> Density
<tb> in <SEP> m2 / g <SEP> in <SEP> mm <SEP> in <SEP> Kgs / 100Kgs <SEP> of <SEP> whole <SEP> vola- <SEP> freeze <SEP> an < SEP> apparent
<tb> black <SEP> tiles <SEP> in% <SEP>% <SEP> in <SEP> Kg / dm3
<tb> Carbon <SEP> black <SEP> ordinary <SEP> 105-140 <SEP> 22-29 <SEP> 125-130 <SEP> 5.0 <SEP> 95.0 <SEP> 4 ;

  5-5 <SEP> 0.16-0.22
<tb> @
<tb> Black <SEP> from <SEP> carbon <SEP> from <SEP> flue <SEP> to
<tb> average <SEP> flow <SEP> 200-210 <SEP> 23-25 <SEP> 105-130 <SEP> 7-7.5 <SEP> 92.5-93 <SEP> 4.0 <SEP > 0.176
<tb> Black <SEP> from <SEP> carbon <SEP> from <SEP> flue <SEP> to
<tb> flow <SEP> low <SEP> 295-360 <SEP> 22-28 <SEP> 88-94 <SEP> 12-13 <SEP> 87-88 <SEP> 3.5 <SEP> 0.192
<tb> Oven <SEP> to <SEP> oil <SEP> conductive <SEP> 125-210 <SEP> 21-29 <SEP> 130-250 <SEP> 1.5-2.0 <SEP> 98-98 , 5 <SEP> 8-8.5 <SEP> 0.095
<tb> Oven <SEP> to <SEP> oil <SEP> 30-125 <SEP> 20-56 <SEP> 80-115 <SEP> 1-1.5 <SEP> 98.5-S9 <SEP> 8 , 5-9 <SEP> Gas oven <SEP> <SEP> 23-30 <SEP> 60-80 <SEP> 70-80 <SEP> 1.0 <SEP> 99.0 <SEP> 9.5-10 <SEP> 0.29
<tb> Thermal <SEP> 6-13 <SEP> 180-470 <SEP> 33-38 <SEP> 0.5 <SEP> 99.5 <SEP> 8.5-9 <SEP> 0,

  50-053.
<tb>
 
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   The specific surfaces were determined by nitrogen absorption using the Brunauer-EmmettTeller method, well known in the art. The particle diameters are the means obtained by arithmetic mean of the measurements taken from electron micrographs of the blacks. Oil absorptions were measured by the Cabot Coherent Ball method using linseed oil. This value is a relative measure of the black structure and the oil required for saturation. The volatile content of a black is related to the amount of chemically adsorbed oxygen present on the carbon surface.

   The pH value of carbon black is determined with a glass electrode in a slurry of water and carbon black, according to the name A.S.T.M. next ; D-1512. Under these conditions, pH is related to the amount of oxygen and carbon complexes existing on the surface of the carbon black. A relatively high amount of these complexes corresponds to low pH.



  Bulk density indicates the amount of storage or cargo space that a given black will occupy.



   The so-called "Cabot Corporation" of Boston, Massachusetts, United States of America, manufactures carbon blacks of the types shown in Table A, and these blacks are sold under the following trademarks "Elf", "Mogil", "Vuloan", and "Sterling". Different quality names may accompany these trademarks.



   The amount of carbonaceous material, eg, coal tar pitch, employed to bind refractory products is large in that higher contents of pitch and the like provide strength.

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 Better mechanical strength in the coked state and better resistance of the refraotaire in the oven. However, larger amounts of pitch also increase the difficulties in manufacturing and storing the bonded refractory.



   As an example, if too much pitch is used, it is difficult to handle the mixture of particles and pitch, because the mixture becomes very sticky. Further, such a mixture does not retain the shape imparted to it by pressing. Since the coal tar pitch is melted at this point, the partial-pitch mixture is too thin to handle if there is too much pitch. The mixture behaves like a deformable plastic mass which does not retain its shape. Further, when the mixture is taken out of a mold, the decrease in pressure tends to show cracks.

   On the other hand, if we keep in a closed position, until the pitch cools and sets, the different parts of the mold or other device used to give the shape, it follows not only that the refraotaire sticks to parts of the mold, but the process as a whole becomes much too slow for it to be applied in industry. Consequently, for a given refractory there is a maximum tolerable capacity or limit on pitch, which balances extreme amounts of pitch sufficient to give a desired binder and a mixture which can retain the shape given by pressing.



   In a variant of the present invention, it has been recognized that a mixture of two particular carbon blacks, used as additives as disclosed in the text, improves the tolerable limit or maximum allowable capacity.

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 pitch, all other conditions being equal. Such a mixture comprises a high oil absorbing carbon black and a thermal carbon black, preferably a fine thermal black. Compared to the separate use of one or the other carbon black, it is this mixture which gives the greatest increase in the mechanical resistance of a refractory in the green state and in the ookified state. .



   The high oil absorbing black can be either a long flow carbon black or a conductive mineral oil furnace carbon black.



   In either case, an absorbent capacity of at least 85 pounds of oil per 100 pounds of black is preferred. Thermal carbon blacks are normally desirable from the standpoint of the strength they impart, these carbon blacks have a relatively coarse particle size. Nonetheless, thermal blacks are the poorest in terms of the tolerable pitch limit and they can even lower that tolerable limit.



   Therefore, the exposed mixture is not only effective in providing desirable strength, but is also effective in increasing the tolerable pitch limit of the pitch.



   The defined mixture of carbon blacks may comprise about 1 to 2 to 2 to 1 by weight of the high oil absorbing black, relative to the thermal black, respectively. Preferably, equal parts by weight of each of the blacks are employed. It is believed that the high oil absorbing black provides an improvement in the tolerable pitch limit, while the thermal black provides the required strength, so that there is a

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   real synergistic cooperation between the two.

   Increases in the allowable pitch content of from 1% to 1.5% by weight have been achieved by using the defined mixture without encountering any of the problems which usually arise with such an increase in pitch. ,
In general, the death-calcined refractory basic particles of the type indicated are first mixed with a carbon black. Any amount of a carbon black confers some advantages, but usually an amount varying from about 0.5% is employed. to about 10%, based on the weight of the total mixture to be finally prepared, and preferably from about 1% to about 3%.

     The mixture or charge is then heated to a temperature ranging from about 107 to 1630, for example, and then brazed with the carbonaceous material, for example coal tar pitch, in an amount of from about 4% to about la% by weight, also relative to the weight of the total mixture. The pitch is preferably preheated to a temperature which renders it only sufficiently fluid that it mixes readily with the refractory particles.



   If the final mixture is not to be used as rammed earth, it is molded to give it a desired shape, for example a brick shape, using high pressure pressing, for example 700 Kg / cm2 and / or by tamping it or vibrating it in an energetic way. After pressing, the shaped refractory is cooled on suitable flat supports to a temperature such that the pitch hardens and the refractory is not susceptible to deformation during handling.

   Once placed in the oven or at another place of use} the

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 Coal tar pitch is transformed into a tough and tough carbonaceous binder by rapidly heating the refractory to a temperature of the order of 1.093 C or even to working temperatures of the order of 1.620 C.

   When the temperature of the mass of the brick crosses the zone between 260 and 980 C, the coal tar pitch is found cracked or "ookefied" by pyrolytic reactions such as those which occur in petroleum cracking towers or. in the manufacture of carbon electrodes which also have an initial binder of coal tar pitch Pyrolytic reactions break down the tar into a light volatile fraction which is removed by distillation and into a residue of carbonaceous material which constitutes the binder.



   If desired, the brick can be "oaked" before use, for example by firing it in any suitable oven having a non-oxidizing atmosphere. By heating, for example, to a temperature of between 37000 and 980 0 for a period of 12 to 72 hours, depending on the size of the bloo, a partial or total pyrolytic decomposition of the pitch is obtained which leaves throughout the 'spread of the brick a carbon residue constituting a tough and resistant binder,
The following examples are set forth, for illustrative purposes only, to more clearly show the invention.



     Any specific enumeration or detail mentioned should be considered as given by way of illustration, since of course the invention is not limited to the procedures and the examples described and can receive various variations falling within the spirit and the scope of the invention. 'invention.

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   In these examples, the strengthening of the binder obtained in accordance with the present invention is indicated by comparing the increase in mechanical resistance to crushing in the coked state of the samples which contain added carbon versus the samples which do not contain. of added carbon.

   The data shown in Tables B to E clearly indicate that the added carbon not only increases the crush strength in the ookified state and the density in the ookified state of the refractory samples, but also improves them. same properties in the samples which have not been ookified and which do not yet possess any carbonaceous binder produced by pyrolytic compositions. The percentages indicated are percentages by weight,
Example 1
A mixture of dead-calcined dolomite comprising 20 parts by weight of a coarse fraction, of which almost 95% passed through a 9-mesh screen, was heated to about 150 ° C and thoroughly mixed.

  525 mm and the whole of which was retained on a sieve with a mesh of 1.68 mm, and 40 parts by weight of an intermediate particle size of which almost 95% passed through a sieve with a mesh of 3.36 mm and of which the substantially all of it was retained on a 0.297 mm mesh screen. It was then heated to about 150 ° C. and to the mixture was added 40 parts by weight of a finely ground death-calcined magnesia, of which almost 65% passed through a mesh screen. of 0.074 mm.

   This granular refractory aggregate was tempered with an addition of 5% of a molten pitch binder having a softening temperature within the range.

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 tervalle ranging from 80 to. 85 C, and it was mixed thoroughly.



  Test samples measuring 90 mm in diameter and about 50 mm in thickness were formed by pressing from the hot load (127-138 C) and under a pressure of 700 Kg / cm2. After they were cooled to room temperature, they were measured for their characteristics in that state, ie in the "or" state, three of the six samples which were pressed from each batch.



  The remaining three samples were heated in the absence of oxygen and were completely ookefied, the samples being measured beforehand and then subjected to compression crushing.



   In the composition described above, the fines of magnesia calcined to death were replaced by 2% very finely pulverized carbon of various types. The addition of carbon to the mixture was accompanied by a correlative reduction in the amount of magnesia fines in order to maintain a uniform particle size distribution in the comparative samples. The carbon was first added to the magnesia fines, ground for 1/2 hour in a roller mill, the thoroughly stirred mixture was heated to. a temperature of about 150 ° C., then a mixture was added to the heated granulated dolomite fraction in order to stir and mix according to the aforementioned technique.

   Table B gives the results of the tests of the types of carbon thus subjected to measurement.



   Example 2
A mixture of dead-calcined dolomite comprising 15 parts by weight of coarse granules passing through a glass was heated to about 150 ° C. and thoroughly mixed.

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 sieve with a 9.525 mm mesh, and retained on a sieve with a 4.7371 mm mesh; 22 parts by weight of intermediate granules passing through a sieve with a 4.7371 mm mesh and retained on a sieve, with a 3.36 mm mesh; and 23 parts. by weight of fine granules passing substantially through a 1.68mm mesh sieve.

   40 parts by weight of heated death-calcined magnesia fines were added to the mixture, and the mixture was then tempered with 4.5% of an addition of molten coal tar pitch having a softening temperature of 1. range from 80 to 85 ° C, and mixed thoroughly. Cylindrical test samples were pressed and subjected to measurement as described in Example 1.



   A 1 to 3 amount of a fine thermal carbon black was replaced by an analogous amount of death cemented magnesia fines. The addition of carbon was carried out as described in Example 1, it was first carried out on the magnesia fines, it was crushed, heated, then mixed as required. described. Table 0 gives the results of the tests corresponding to these substitutions.



   Example 3
By employing the same granular refractory composition and the procedure of Example 2, including the 2% carbon increases to the magnesia fines, the coal tar pitch percentages were increased. Three different carbon blacks were used to substitute for the magnesia fines. The comparison of the results of tests carried out on the resulting test samples indicates the improved properties of the samples containing carbon additions compared to those without.

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 No addition of carbon, depending on the various pitch percentages. Table D shows this comparison.



     Example 4
It was shown in Example 3 and in Table D that an increase in the pitch content increases the mechanical strength of the refractory, but not as markedly as is the case with the 2% substitution. from fine thermal black to the fine fraction of a granular refractory mixture. Attempts to increase the weight content of this mixture have resulted in excessively plastic and unworkable masses being obtained.



  It has, however, been recognized that small additions of medium carbon black flange to granular refractory mixtures containing fine thermal carbon black make the addition of pitch up to 6% possible, giving refractories the advantages of high quality. higher pitch content.



   In this example, a temperature of about 15000 was heated and thoroughly mixed a mixture of dead-calcined dolomite containing 15 parts by weight of coarse granules sieved so as to pass through a sieve. . mesh of 9.525 mm and to be retained on a sieve with mesh of 4.7371 mm;

   22 parts of intermediate size grain sieved so as to pass through a sieve with a 4.7371 mm mesh and be retained on a sieve with a 3.36 mm mesh; and 23 parts of the feed composed of graded granules passing substantially through a 3.36mm mesh sieve. To about 15,000 was heated and to the dolomite fraction was added the finely divided dead calcined magnesia constituting 38 parts of the charge and of which almost 65% passed through a mesh screen.

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 the 0.074 mm.



   To the magnesia fines were added 2 parts by weight of a carbon black, ground for 1/2 hour, heated, stirred with the granules of dead-calcined dolomite, mixed with salt. pitch, and cylindrical test specimens were made by pressing as described in Examples 1 to 3. The carbon black of this example consisted of fine thermal carbon black, medium carbon black, or carbon black. mixture of these blacks. A conductive oil-fired carbon black could have been used, instead of the medium-sized carbon black. The percentage of weight added varied from 4.5 to 6%.



   Table B gives the results of addition tests of various types of carbon for a tempered granular refractory mixture without varying amounts of coal tar pitch.
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   TABLE B
Density and resistance measurements
Crushing of raw and ookefied samples 90 mm in diameter by 50 mm high
Cold pressed under a pressure of 700 Kg / om2 Composition::
 EMI20.1
 Dolomite -calcine a. dead, coarse 20% by weight
 EMI20.2
 
<tb>
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead, <SEP> average <SEP> 40 <SEP>% <SEP> in <SEP> weight
<tb> Fine <SEP> of <SEP> chalk <SEP> calcined <SEP> to <SEP> dead <SEP> 38 <SEP> to <SEP> 40 <SEP>%
<tb> Addition <SEP> of <SEP> carbon <SEP> 2 <SEP>%
<tb> Density <SEP> in <SEP> Kg / dm3 <SEP> Resistance <SEP> at
<tb> 1 '<SEP> overwrite <SEP>
<tb> in <SEP> Kg / om2
<tb>
 
 EMI20.3
 Type 0 in state in state in state in state oai '>' bone.3E oarljone poia;

   # .... 9 ..... ## 2adglé cru 2.2hdiue
 EMI20.4
 
<tb>
<tb> None
<tb>
 
 EMI20.5
 (éohantil- '
 EMI20.6
 
<tb>
<tb> Ion <SEP> indicator) <SEP> 0 <SEP> 5.0 <SEP> 0.277 <SEP> 0.264 <SEP> 499 <SEP> 274
<tb> Black <SEP> thermal <SEP> fine <SEP> 2 <SEP> 5.0 <SEP> 0.282 <SEP> 0.273 <SEP> 752 <SEP> 674
<tb> Black <SEP> thermal <SEP> fine <SEP> 2 <SEP> 5.0 <SEP> 0.282 <SEP> 0.271 <SEP> 696 <SEP> 562
<tb> Black <SEP> from
<tb>
<tb> flue
<tb> ordinary <SEP> 2 <SEP> 5.0 <SEP> 0.281 <SEP> 0.271 <SEP> 604 <SEP> 449
<tb> Black <SEP> from
<tb> oarneau
<tb> flow
<tb> long <SEP> 2 <SEP> 5.0 <SEP> 0.276 <SEP> 0.268 <SEP> 471 <SEP> 372
<tb>
 
 EMI20.7
 K Encycloprdia of Chemioal Technology "by Kirk and

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 Othmer, edited by "The Interscience Enoyolopedia" Ino.



    New-York 1949, volume 3, pages 34 to 60.



   The adhesive properties of the coal tar pitch binder on the refractory granules also appear to be improved by the addition of pulverized carbon. Refractory samples which generally have not been coked show a marked improvement in uncured compressive crush strength compared to -% of analogous samples on which no addition was made As shown in Table C, the addition of carbon from 1 to 3% significantly increases the desirable properties of the refractory using pitch as a binder.

   But up to 10% carbon can be added without having any nooj effect on the refractory.
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   TABLE C Measurement of density and resistance to crushing of raw and ookefied samples 90 mm in diameter and 50 mm high Formed by pressing under a pressure of @ 700 Kg / cm2.
 EMI22.1
 
<tb>
<tb>



  Composition <SEP>:
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead, <SEP> coarse <SEP> 15 <SEP>% <SEP> in <SEP> weight
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead, <SEP> average <SEP> 22 <SEP>% <SEP> in <SEP> weight
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead, <SEP> fine <SEP> 23 <SEP>% <SEP> in <SEP> weight
<tb> Fine <SEP> of <SEP> Chalk <SEP> calcined <SEP> to <SEP> dead <SEP> 37 <SEP> to <SEP> 40 <SEP>% <SEP>)

   <SEP> 40 <SEP>% <SEP> en
<tb> Addition <SEP> of <SEP> carbon <SEP> 0 <SEP> to <SEP> 3 <SEP>% <SEP> weight
<tb> Density <SEP> in <SEP> Kg / dm3 <SEP> Resistance <SEP> at
<tb> 1 '<SEP> overwrite <SEP>
<tb> in <SEP> Kg / cm2
<tb> Type <SEP> from <SEP>% <SEP>% <SEP> to <SEP> state <SEP> to <SEP> state <SEP> to <SEP> state <SEP> to <SEP> state
<tb> carbon <SEP> carbon <SEP> pitch <SEP> oru <SEP> coked <SEP> oru <SEP> coked
<tb> None
<tb> (sample <SEP> control) <SEP> 0.0 <SEP> 4.5 <SEP> 0.287 <SEP> 0.268 <SEP> 541 <SEP> 189
<tb> Thermal
<tb> end <SEP> 1.0 <SEP> 4.5 <SEP> 0.294 <SEP> 0.279 <SEP> 759 <SEP> 428
<tb>
<tb> Thermal
<tb> end <SEP> 1.5 <SEP> 4.5 <SEP> 0.295 <SEP> 0.284 <SEP> 885 <SEP> 520
<tb> Thermal
<tb> end <SEP> 2,0 <SEP> 4, <SEP> 5 <SEP> 0.296 <SEP> 0, <SEP> 286 <SEP> 878 <SEP> 710
<tb> Thermal
<tb> end <SEP> 2.5 <SEP> 4.5 <SEP> 0,

   <SEP> 297 <SEP> 0.284 <SEP> 1012 <SEP> 590
<tb> Thermal
<tb> end <SEP> 3.0 <SEP> 4.5 <SEP> 0.298 <SEP> '0.286 <SEP> 815 <SEP> 681
<tb>
 

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TABLE D
Density and crush resistance measurement of raw and coked samples 90mm in diameter and 50mm high Formas by pressing under pressure,
700 Kg / om2, Composition
 EMI23.1
 
<tb>
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead, <SEP> coarse <SEP> 15 <SEP>% <SEP> in <SEP> weight
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead, <SEP> average <SEP> 22 <SEP> in <SEP> weight
<tb> Dolomite <SEP> calcined <SEP> 4 <SEP> dead, <SEP> fine <SEP> 23 <SEP>% <SEP> in <SEP> weight
<tb> Fine <SEP> of <SEP> magnesia <SEP> oaloined <SEP> to <SEP> dead <SEP> 38 <SEP> to <SEP> 40 <SEP>)

   <SEP> 40 <SEP>% <SEP> en
<tb> Addition <SEP> of <SEP> carbon <SEP> 0 <SEP> to <SEP> 2 <SEP>% <SEP> 3 <SEP> weight
<tb>
 
 EMI23.2
 

 <Desc / Clms Page number 24>

 
 EMI24.1
 ! 1) 4BU: Q (Continued)
 EMI24.2
 Density in Ksldm31R4e: Lsl1e.nQe at flaring I in. Kg / om2 Type of bzz, 'àa' state to state in carbon state qay'bQM, po3, x.

   qrn, çkëfl oofld
 EMI24.3
 
<tb>
<tb> None
<tb>
 
 EMI24.4
 (o! 1sntU-
 EMI24.5
 
<tb>
<tb> Ion <SEP> indicator) <SEP> 0.0 <SEP> 4, <SEP> 5 <SEP> 0.287 <SEP> 0.268 <SEP> 541 <SEP> 189
<tb> Thermal
<tb> end <SEP> 2.0 <SEP> 4.5 <SEP> 0.208 <SEP> 0, <SEP> 286 <SEP> 878 <SEP> 715
<tb> None
<tb> (sample <SEP> control) <SEP> 0.0 <SEP> 5.5 <SEP> 0.294 <SEP> 0.279 <SEP> 777- <SEP> 448
<tb> Black <SEP> from
<tb> carbon
<tb> ordinary <SEP> 2.0 <SEP> 5.5 <SEP> 0, @ 94 <SEP> 0.286 <SEP> 843 <SEP> 703
<tb> None
<tb> (sample <SEP> control) <SEP> 0.0 <SEP> 6.0 <SEP> 0.292 <SEP> 0.282 <SEP> 703 <SEP> 562
<tb> Black <SEP> from
<tb> carbon <SEP> at
<tb> flow
<tb> long <SEP> 2,0 <SEP> 6,0 <SEP> 0.292 <SEP> 0,

  284 <SEP> 843 <SEP> 773
<tb>
 
 EMI24.6
 

 <Desc / Clms Page number 25>

 
TABLE E
Density and crush resistance measurement of raw and ookefied samples 90 mm in diameter and 50 mm high
Shapes by pressing under a pressure of
700 Kg / om2.



    Composition::
 EMI25.1
 
<tb>
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead <SEP> coarse <SEP> 15 <SEP>% <SEP> in <SEP> weight
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead <SEP> average <SEP> 22 <SEP>% <SEP> in <SEP> weight
<tb> Dolomite <SEP> calcined <SEP> to <SEP> dead <SEP> fine <SEP> 23 <SEP>% <SEP> in <SEP> weight
<tb> Fine <SEP> from <SEP> chalk <SEP> calcined <SEP> to <SEP> dead <SEP> 38 <SEP> to <SEP> 40 <SEP> in <SEP> weight
<tb> Addition <SEP> of <SEP> carbon <SEP> 2 <SEP>% <SEP> in <SEP> weight
<tb>
 
 EMI25.2
 

 <Desc / Clms Page number 26>

   Table E (continued)

     
 EMI26.1
 
<tb> Résistanca <SEP> to <SEP> overwriting
<tb> Density <SEP> in <SEP> kg / dm3 <SEP> in <SEP> kg / cm2
<tb> Carbon <SEP> type <SEP>% <SEP>% <SEP> to <SEP> state <SEP> to <SEP> state <SEP> to <SEP> state <SEP> to <SEP> state <SEP>
<tb> carbon <SEP> pitch <SEP> raw <SEP> coked <SEP> raw <SEP> coked
<tb> Thermal <SEP> end <SEP> 2.0 <SEP> 4.5 <SEP> 0.297 <SEP> 0.284 <SEP> 984 <SEP> 689
<tb> Thermal <SEP> end <SEP> 1.75 <SEP> 4.5 <SEP> 0.297 <SEP> 0.282 <SEP> 822 <SEP> 689
<tb> Flue <SEP> to <SEP> flow <SEP> long <SEP> 0.25
<tb> Thermal <SEP> end <SEP> 1.50 <SEP> 4.5 <SEP> 0.297 <SEP> 0.284 <SEP> 913 <SEP> 773
<tb> Flue <SEP> to <SEP> flow <SEP> long <SEP> 0.50
<tb> Flue <SEP> to <SEP> flow <SEP> long <SEP> 2.0 <SEP> 5.0 <SEP> 0.290 <SEP> 0.279 <SEP> 752 <SEP> 506
<tb> Thermal <SEP> end <SEP> 1,

  25 <SEP> 5.0 <SEP> 0.298 <SEP> 0.286 <SEP> 1012 <SEP> 639
<tb> Cerneau <SEP> to <SEP> flow <SEP> long <SEP> 0.75
<tb> Thermal <SEP> end <SEP> 1.0 <SEP> 5.0 <SEP> 0.295 <SEP> 0.284 <SEP> 963 <SEP> b89
<tb> Flue <SEP> to <SEP> flow <SEP> long <SEP> 1.0
<tb> Thermal <SEP> end <SEP> 0.5 <SEP> 5.0 <SEP> 0.293 <SEP> 0.281 <SEP> 808 <SEP> 611
<tb> Flue <SEP> to <SEP> flow <SEP> long <SEP> 1.5
<tb>
 

 <Desc / Clms Page number 27>

 
The carbonaceous material binder per se is not considered new in this improved refractory composition using pitch as a binder, but since its concentration influences the formation of carbonaceous binder, preferably a weight percent of 4% to 10% approximately.

   Increasing the binder weight content improves some properties of the refractory, but the additions of pulverized carbon to these compositions increase the desired properties above those corresponding to similar pitch contents. Table D shows the comparison of various pitch contents with and without the addition of carbon.



   The nature of the carbon bond is also influenced by the initial c -bond material chosen for the binder of the refraotaire. The pitch binder can be chosen according to its softening point, for example 41 - 44 C
80 - 85 0
90 - 95 C 100 - 105 C based on the desired end result but preferably a pitch having a softening point between 80 and 85 C. is used.
 EMI27.1



    

Claims (1)

ABSTRACT A. Method of mixing basic refractory particles with a sufficient quantity of carbon material capable of pyrolytically decomposing and chosen from the group comprising pitch, coal tar and bituminous asphalts in order to bind together said particles, the method being characterized by the following points taken singly or in combination: 1) It consists of adding to the mixture from about 0.5 to about 10% by weight based on the weight of the total mixture of pulverized carbon black with a non-crystalline structure. 2) The process is employed to form a refractory article in the gold state, the particles of basic refractory are particles of basic refractory calcined to death, the carbonaceous material is pitch, and the mixture is then formed under pressure ; the addition of finely divided carbon black is carried out in the mixture before shaping, 3) Pitch is the pitch of coal tar, the mixture is heated to pyrolytically decompose the pitch and form a carbon bond between the particles; 0.5-10% by weight based on the weight of the total mixture of carbon black is added before heating the sprayed carbon black in order to improve the properties of the resulting bonded refractory. 4) The particles are stirred with from about 4% to about 10% by weight of the coal tar pitch mixture, then heated to cool the mixture and form a bonded mass; the addition of powdered carbon black to the <Desc / Clms Page number 29> EMI29.1 heck useful rAdIange before heating: Cage increases the v.ef mixing temperature before heating increases the life -high temperature of the bonded mass. 5) The refractory particles are chosen from the group comprising dead calcined dolomite dead calcined magnesia and mixed them with these orpa, 6) Carbon black is chosen from the group consisting of lamp naira, kernel blacka $ furnace combustion blacks, thermal blacks, and acetylene blacks *. 7) Carbon black has properties within the following ranges: Average particle diameter 20 to 500 millimocrons Specific surface area 5 to 367 m2 / gram Material content va ?. biles Less than 14% by weight Fixed carbon 85 to 99.5% by weight 8) Carbon black consists essentially of a mixture of a carbon black with high oil absorbing power and a thermal carbon black. 9) Carbon black consists essentially of a mixture of a carbon black with a high capacity of oil absorption, having an oil absorption of at least 85 kg of oil per 100 kg of black, and a thermal carbon black, these carbon blacks being present in a weight ratio of 2 to 1 to 1 to 2 respectively. 10) Carbon black consists of a mixture of approximately equal parts by weight of a high oil absorbing carbon black selected from the group consisting of a conductive oil furnace carbon black and a long flow carbon black oil having an oil absorption of at least 85 kg of oil for <Desc / Clms Page number 30> 100 Kgs of black, and a fine thermal carbon black. 11) To the mixture of refractive particles are added a and. of tar pitch, before heating, an amount of 1% to about 3% by weight of finely divided carbon black having properties between the following limits Average particle sizes 120 to 500 millimicrons Specific Surface 6 to 13 m2 / gram Content in volatile matter Less than 1% by weight. Fixed carbon 95 to 99.5% by weight B. As a new industrial product, a refraotary article manufactured characterized by the fact that it is manufactured according to the process according to A.